The present techniques relate generally to electronic devices. More specifically, the techniques relate to methods and systems for sealing structures in electronic devices.
Certain electronic devices have components that may be sensitive to adverse environmental conditions, including water vapor and oxygen. For example, display devices are commonly used as screens or displays for a wide variety of electronic devices, including televisions, portable and desktop computers, and handheld devices, such as cellular telephones, personal data assistants, and media players. The display components of such devices may display images by producing patterns of light in response to electrical signals. The patterns of light, or the images and graphics formed by the display device may be formed by individual light emitting structures, such as organic light emitting diodes (OLEDs). OLEDs may be optoelectronic devices having several layers of organic materials, and may include a pair of electrodes, and multiple layers of electroluminescent materials between the electrodes. For example, an OLED may typically include a substrate, an anode, a hole-transporting layer made of an organic compound, an organic luminescent layer with suitable dopants, an electron transport layer, and a cathode.
Light emitting structures, including OLEDs, may be prone to degradation under certain environmental conditions such as oxygen, moisture, chemicals, or other contaminants. For example, water vapor and oxygen ingress over time may cause degradation of light emitting polymers, undesired reactions at the electrode-organic layer interfaces, corrosion of metals, or undesired migration of ionic species, etc. Such degradation may result in the growth of dark spots, delamination, and/or the lateral shrinking of the emissive areas of the light emitting structure. Dark spots, delamination, and/or shrinking of the emissive areas of such structures may affect the quality and/or uniformity of the image displayed.
To minimize the degradation of electronic devices, such as light emitting structures, the structures may be hermetically sealed with thin film barrier coatings to protect against adverse environmental conditions. However, such coatings may provide only limited protection by substantially covering the top of the device. For example, for a bottom emission OLED, the top of the device would constitute at least complete coverage over the cathode area defining the active light emitting portion. While barrier coatings may protect the top of the structure, oxygen, moisture, or other contaminants may still diffuse laterally into the structures due to insufficient protection of the edges of the device by the same barrier coating. Such diffusion may corrode or degrade light emitting structures laterally, possibly decreasing the electroluminescent area of the structure over time.